Research examines how fast ice sheets respond to climate change

UB students (left to right) Elizabeth Thomas, Sean McGrane and
Nicolas Young on Baffin Island. They were members of a team
studying the historical extent of glaciers on the Arctic
island. Photo: Jason Briner

“What we’re seeing is that these ice sheets are surprisingly sensitive to even short periods of temperature change.”

Jason Briner, Associate Professor

UB Department of Geology

A new Arctic study in the journal Science is helping to unravel
an important mystery surrounding climate change: how quickly
glaciers can melt and grow in response to shifts in
temperature.

According to the new research, glaciers on Canada’s Baffin
Island expanded rapidly during a brief cold snap about 8,200 years
ago. The discovery adds to a growing body of evidence showing that
ice sheets reacted rapidly in the past to cooling or warming,
raising concerns that they could do so again as the Earth heats
up.

“One of the questions scientists have been asking is how
long it takes for these huge chunks of ice to respond to a global
climate phenomenon,” says study co-author Jason Briner, UB
associate professor of geology. “People don’t know
whether glaciers can respond quickly enough to matter to our
grandchildren, and we’re trying to answer this from a
geological perspective by looking at Earth’s history.

“What we’re seeing,” he adds, “is that
these ice sheets are surprisingly sensitive to even short periods
of temperature change.”

Briner’s colleagues on the study include lead author
Nicolás Young, who worked on the study as part of his PhD at
UB and is now a postdoctoral researcher at Columbia
University’s Lamont-Doherty Earth Observatory; Dylan H. Rood
of the Scottish Universities Environmental Research Centre and the
University of California-Santa Barbara; and Robert C. Finkel of UC
Berkeley.

The research found that mountain glaciers on Baffin Island,
along with a massive North American ice sheet, expanded quickly
when the Earth cooled about 8,200 years ago.

The finding was surprising because the cold snap was extremely
short-lived: The temperature fell for only a few decades and then
returned to previous levels within 150 years or so.

“It’s not at all amazing that a small local glacier
would grow in response to an event like this, but it is incredible
that a large ice sheet would do the same,” Young says.

To conduct the research, Briner led a team to Baffin Island to
read the landscape for clues about the pre-historical size and
activity of glaciers that covered the island.

Moraines—piles of rocks and debris that glaciers deposit
while expanding—provided valuable information. By dating
these and other geological features, the scientists were able to
deduce that glaciers expanded rapidly on Baffin Island about 8,200
years ago, a period coinciding with a short-lived cold snap.

The researchers also found that Baffin Island’s glaciers
appeared to have been larger during this brief period of cooling
than during the Younger Dryas period, a much more severe episode of
cooling that began about 13,000 years ago and lasted more than a
millennium.

This counterintuitive finding suggests that unexpected factors
may govern a glacier’s response to climate change.

With regard to Baffin Island, the study’s authors say that
while overall cooling may have been more intense during the Younger
Dryas, summer temperatures actually may have decreased more during
the shift 8,200 years ago. These colder summers could have fueled
the glaciers’ rapid advance, decreasing the length of time
that ice melted during the summer.

Detailed analyses of this kind will be critical to developing
accurate models for predicting how future climate change will
affect glaciers around the world, Briner says.